1. Field of the Invention
The present invention relates generally to the field of ventilation devices and more particularly to an improved vent that provides desirable venting, prevents water entry, and prevents the penetration of a pry bar or a probe wire beyond the vent.
2. Description of the Related Art
Equipment enclosures are provided to prevent access to the enclosed equipment by unauthorized people and also provide for the protection of the enclosed equipment from the environment. Vents for enclosures are provided to prevent the buildup of moisture and heat inside the enclosures. The venting arrangement, therefore, must provide for the free passage of air, prevent water entry, and prevent access to the enclosure by tampering. For example, tampering may occur by the attempted insertion of a variety of objects into the vent openings such as sticks or elongated metal members in the form of pry bars or wires. Accordingly, to the fullest extent possible, the venting arrangement should deter the entry by animals or unauthorized persons regardless of their determination and persistence. Of course, it is not possible to make any enclosure totally impenetrable, but the enclosure should be tamper resistant to the limits of technical feasibility.
Standards such as ANSI C57.12.28 aid in the development of desirable standards to resist tampering. Such standards are developed in terms of specific tests involving specific tampering items or devices that might be expected to be utilized by tamperers. Of course, while the tampering tests encompassed by the standards involve persistent illegal conduct, it is still important to manufacture equipment so as to attempt to protect such tamperers from themselves and their conduct, as well as to protect small children who may come along after the tamperer. Thus, the standards and the tests enumerated therein are performed to determine the effectiveness of a comprehensive integrity system. One sequence of specific tests involve the use of a pry bar of predetermined dimensions including a wedge shaped chisel tip of 2 inches in length that tapers from 0.4 into to 0.1 inch in thickness, with a uniform width of 0.5 inch. Additionally, a probe wire is utilized that is bare number 14 AWG soft-drawn solid copper wire 10 feet long. For the sequence test, the pry bar is utilized to attempt to gain entry and thereafter the wire probe is manipulated in an attempt to gain entry. Push and pull tools are also defined for various other tests.
Examples of various tamper-resistant enclosures are shown in U.S. Pat. Nos. 4,102,475 and 4,963,696. A vent structure for high-voltage electrical equipment is shown in U.S. Pat. No. 4,073,000 and at pages 5 and 23 of Descriptive Bulletin 621-30 dated Aug. 25, 1986 by S&C Electric Company, Chicago, Ill. That vent includes a pattern of openings or louvers in the exterior panel of the enclosure and a recessed baffle with louvers on the interior surface of the panel. Additionally, wire-mesh screening is provided internal to the recessed baffle.
While these arrangements have been effective for their intended purposes, it is always extremely desirable to provide improved tamper-resistant vent arrangements for enclosures in an attempt to advance the state of the art and to prevent unauthorized, dangerous, and illegal ingress to equipment.